On Saturday, January 12, 2019 at 6:59:15 PM UTC-5, Lawrence Crowell wrote:   
   > On Tuesday, January 8, 2019 at 10:49:54 PM UTC-6, toadast...@gmail.com wrote:   
   > > 04-JAN-2019   
   > >   
   > > Happy new year to all -   
   > >   
   > > Question:   
   > >   
   > > What physical status (within a given model) should be given   
   > > to the property of "computability?"  For example, in the case   
   > > of the information loss paradox, information clearly has   
   > > a physical status, otherwise perfectly rational physicists   
   > > wouldn't get so upset about losing it.   
   > >   
   > > So if the unitary evolution of a system -- in the form   
   > > of unit probability as sum of all relevant systemic   
   > > probabilities -- is, in principle, "computable," then   
   > > what ponderable status should be ascribed to   
   > > the notion of computability?   
   > >   
   > > Cheers,   
   > > mj horn   
   >   
   > Shannon, or really Shannon-Khinchin, entropy S = -k sum_n P(n)log[P(n)]   
   > points to information as a physical quantity. This is carried further   
   > with von Neumann entropy and quantum information. The transformations of   
   > state quantum mechanically is unitary and it is not difficult to show   
   > that entropy is constant. To the extent we consider these to be "quantum   
   > computations" it would mean that anything computable is also observable.   
      
   13-JAN-2019   
      
   But of the property of computability itself?   
      
   How can I even estimate it, as I would estimate the sea-worthiness of   
   a boat or the air-worthiness of an aircraft?   
      
   If I look at an automobile I observe very little sea-worthiness and   
   almost no air-worthiness.  What am I observing?  Information or its   
   absence?   
      
   How can computability be observed and measured?   
      
   cheers,   
   mj horn   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)